Information signals, such as media signals and especially compressed video and audio streams and packetized audio and video streams propagate over a medium such as communication channels, and especially terrestrial, wireless, satellite and cable communication channels. Video streams usually include a relatively large amount of information and are usually stored in storage units and transmitted over communication channels in a compressed form.
The Moving Pictures Experts Group (MPEG) specifications are standardized methods for compressing and transmitting media signals such as video and audio.
As media signals, such as media signal arranged in streams, sequences of media signals and the like are transmitted over communication channels there is a need to match the bit rate of the media streams to the available bandwidth of the communication channels or to an available storage space of a storage unit. This match usually requires a reduction of the bit rate of the media streams. Very frequently, the bandwidth of even a compressed representation of a media stream requires more bandwidth than available and the transmission of the entire media stream is not feasible. Furthermore, a loss of media stream portions, such as packets conveying the media stream may result in severe quality degradation.
There is a need to provide methods and systems for a compact representation of a media stream. There is a further need to provide systems and methods for robust transmission methods of media streams, and especially systems and methods for allowing for recovering from a loss of some portions of the media stream. There is yet a further need to provide systems and methods for an efficient utilization of prioritized communication channels, quality of service communication channels and differential-service-supporting communication channels. There is another need to provide systems and methods for secure transmission of media streams. There is yet another need to provide an effective system and method for transmitting representations of media streams over variable bandwidth channels. There is a need to provide systems and methods for efficiently reconstructing a media stream from various representations of the media stream.